Spectrum Computing

Well, I really wish Z80 had more addressing modes. Once you try 6809, you see how much time you waste with pointer arithmetic on Z80. Otherwise, LDI, LDD would be nice without prefix. And yes, CALL cc are used less than one would expect. My ideal 8 bit CPU would be mix of 6809 and ZB0, possibly wit...

This is probably more of a general Z80 question rather than applying to the Spectrum specifically, but do you think when Zilog designed and implemented the Z80's instructions and assigned them to either 1 or more byte opcodes that they always made the right choice? I'm not really talking about hypot...

Video clip of teleporting in Quadron at 7m 7s:

Yes, Happy Christmas everyone

Enjoy the day. I'm sure those of you unwrapping your Nexts today are sure to!

Summer 1982, England.
Mail order 16K Spectrum. Fab!

No no, it has a mushroom head, like Microbot, and lives in a circuit board firing lightning bolts. There are some gates/chips that teleports you away... I found a screenshot from the bootleg "Microdroid" (which is funny because it sounds like Microbot BUT IT'S NOT). https://i.postimg.cc/w...

Quadron

I hadn't remembered this, but according to my programming notes from the Spectrum era, I'd had the computer replaced or repaired 4 times over a 6 year period... hardly impressive reliability! My first Spectrum was from the early mail order days, so maybe there were more teething problems back then, ...

After I'd downloaded specemu-3.4.b110623, MalwareBytes warned me it considered one of the zip's contained files " emulib.dll " a threat: Neshta.Virus.FileInfector.DDS Symptoms To gain persistence, Virus.Neshta changes the default value for the registry key HKEY_CLASSES_ROOT\exefile\shell\o...

Late to the discussion with not much new to add - but I just got my old Amiga out the loft and I'm meaning to test it out. Moved to the Amiga from Spectrum + SAM in the late eighties, the OS, the graphics and sound were very impressive but in my opinion fancier graphics are no substitute for gamepl...

Aha! Using some of the neat debugging techniques suggested here I was thankfully able to find and fix the intermittent crash I was experiencing. It was to do with an interaction between my IM2 service routine and code in the main game loop. I'd assumed the interrupt code and the game code operated o...

Some fantastic suggestions, thanks!

And when I track this bug down I'll post back here what it was.

Wondered if anyone had a good approach to debugging rare, intermittent crashes in Z80 code. My normal method of debugging is to print expected values on screen and delve deeper if they don't align with my expectations, or use the debugger to step through the recently added code, or add breakpoints (...

They didn't. They just drew sprites from the bottom up, so they wouldn't get into any beam-racing situations. Instead, you just get a single-frame twinkle when a sprite is being drawn across the beam, which isn't very noticeable. One more thing is that they erase and redraw each sprite one by one, ...

Yes, I made a generalization about most Speccy games being fairly jerky when compared to the arcade "standard" of graphics updating 50 times a second, which you very rarely saw in Speccy games, especially when scrolling was involved (one rare example for a game with scrolling would be the...

Stefan wrote: ↑Fri Mar 10, 2023 10:23 pm I’ll see your Psytraxx and raise you an Explorer.

Psytraxx had 1025 screens. Of course they were all rather samey, with some procedural generation cheats, but pretty big for its time in '84!

You rich kids and your “buttons.” I remember a B&W TV we had (pre-Speccy) with a channel selector knob. The plastic knob had broken off, so we used pliers to grab the metal selector stub and switch channels (thonk-thonk-thonk!). You rich kids with flashy knobs. My old B&W TV was so basic in...

Initially I was hooking up my ZX81 to the shared (Granada?) family TV in the living room. After about a year I got a small B&W TV for my birthday that I had in my bedroom. I continued using that TV after I'd saved up for the Spectrum, so just shades of grey for me to start with, unless I wanted ...

Hi, Sorry for the tardy response! The way to do it with Inkspector (it's easier with the new 2.0.4 release so I'd suggest you upgrade any older version first) is to add a breakpoint with the following settings: ... HTH Inky. Thanks Inky - really helps. Expecially coupled with the debugger's inheren...

What happens if you ask it again, after telling it there is no END. Does it learn fro its mistake? I don't think it does (not yet at least!), because it made exactly the same mistake back in December, as evidenced here where the human points out there isn't an END statement in Spectrum BASIC, it ap...

I'd like to second that.. Happy Christmas to all!

have you got that piece of code? I might have that little piece of paper somewhere. I remember it was a 1 or 2 line REM statement with a bunch of seemingly random graphic symbols, letters and numbers, ending with a TAN statement (which I would later learn was the ZX81's character code for the Z80's...

So learning assembler was a gradual process spurned on by the immense speed it offered, together with the allure of being able to write your own "arcade quality" games. Whoops :oops:. I meant to type: So learning assembler was a gradual process spurred on by the immense speed it offered, ...

A friend passed me a scrap of paper in school during a chemistry lesson. There were some crypric symbols and letters written on it, and he said to type it into the ZX81. It was a REM statement and after typing it all in back at home, and issuing the final command, a USR statement, my mind was blown!...

QAOPM feels pretty natural on the rubber keyed Spectrum. Or equally AZOPM. Right thumb feels just about in the right place for Fire. In a pinch 67890 (using the interface 2 option) works for games with unwieldy key choices and no redefine option. Or even cursor keys! I think that's a throwback from ...